The filter() function is used for returning an iterator, here the elements are filtered through the function.it helps to test each element in the sequence to be true or not.
filter(function, iterable) #Where iterable can be a list, string, tuple, dictionary , set etc
It takes functions and iterable as parameters.
| Parameter | Description | Required / Optional |
|---|---|---|
| function | A function that tests if the element is accepted or not | Required |
| iterable | Iterable may be a set, lists, tuples, etc... | Required |
| Input | Return Value |
|---|---|
| iterable(if element) | iterator(filtered list) |
| iterable(if not element) | False |
# list of letters
letters = ['a', 'b', 'd', 'e', 'i', 'j', 'o']
# function that filters vowels
def filter_vowels(letter):
vowels = ['a', 'e', 'i', 'o', 'u']
if(letter in vowels):
return True
else:
return False
filtered_vowels = filter(filter_vowels, letters)
print('The filtered vowels are:')
for vowel in filtered_vowels:
print(vowel)
Output:
The filtered vowels are: a e i o
# Returns the elements which are multiples of 5
def multipleOf5(n):
if(n % 5 == 0):
return n
myList = [10, 25, 17, 9, 30, -5]
myList2 = list(filter(multipleOf5, myList))
print(myList2)
Output:
[10, 25, 30, -5]
# random list
random_list = [1, 'a', 0, False, True, '0']
filtered_list = filter(None, random_list)
print('The filtered elements are:')
for element in filtered_list:
print(element)
Output:
The filtered elements are: 1 a True 0
